1. Field of the Invention
Volume-measuring instruments are known for gas and water as well as electricity meters for the measurement of the energy that has flown therethrough, in which the measured volume or the measured energy are transmitted to a mechanical counting wheel mechanism with a step-down ratio adapted to the measuring instrument. The counting wheel mechanism in that case indicates a quantity that has flown therethrough since the last zero setting or since the commissioning or start-up of the instrument. In order to ascertain the consumption during a certain period, the state or setting of the counting wheel mechanism is read at both the beginning and the end of this period.
2. Discussion of the Background of the Invention and Material Information
A preferred construction for the counter read-out of a counting wheel mechanism consists of an axle, on which the counting wheels are mounted so as to be rotatable with respect thereto and on the circumference of the wheels the numerals 0 to 9 are applied, as well as of a second axle having shift pinions rotatably mounted thereon in such a manner that the lower digit counting wheel, in the last tenth of a revolution, each time by way of the associated shift pinion, steps or advances the next higher digit wheel by one tenth of a revolution. A counting wheel mechanism for a water measuring instrument is set forth, for example, in German Patent Publication DE 22 44 404 A1. Depending upon the construction of the measuring instrument, it is important for the achievement of a wide measuring range, with good measuring accuracy, to keep the torque required for driving the counting wheel mechanism as small as possible.
A solution for the electronic read-out of a counting mechanism, in which the continuous rotational movement of the counting wheels is translated into snap movement, is set forth in U.S. Pat. No. 3,732,404. For this purpose, it must be assumed that the spring, or the like, used for the snap movement stores sufficient energy in order to turn the entire wheel counting mechanism or packet forward by one setting or step, for example, from 19,999 to 20,000. A solution, which permits the electronic read-out for a counting mechanism of the needle type, with the use of mechanical contacts without snap movement, is set forth in European Patent Publication EP 20 27 22 B1. It is of course also possible to use a counting mechanism of the needle type in synchronism with the counting mechanism of a wheel counting mechanism.
A rotational angle sensor, which is suitable for the electronic reading-out of a counting wheel mechanism, is described, for example, in yet unpublished Swiss Patent Application CH 02 059/93-5, filed Jul. 11, 1993 and also assigned to the Assignee of this invention. Another suitable rotational angle sensor comprises rotary capacitors that are connected with the counting wheels, which are to be read, and with an associated electronic evaluating system.
A readily rotatable counting wheel mechanism with low driving torque has a certain amount of mechanical rotary play between the individual counting wheels, which play can add up, over several counting wheels, to a large angle of rotation when the counting wheels are in engagement with the shift pinion. Wheels not disposed in a shift engagement are fixed in their setting, apart from a small amount of play, by the associated shift pinion. The rotational play between counting wheels disposed in a shift engagement, on one hand, and the fixing of the counting wheels, not disposed in such an engagement, on the other hand, causes, in multidigit wheel mechanisms, that the indicated numeral on a counting wheel cannot, in all cases, be reliably recognized from the instantaneous angle of rotation of the corresponding counting wheel.